Attribute Value Properties for Test Selection with Cartesian Product Models

ABSTRACT

A method for modeling a test space is provided. The method comprises defining a coverage model including one or more attributes, wherein respective values for the attributes are assigned, one or more definitions of value properties for said attributes with assigned values, and one or more requirements that limit combination of attribute values that are legal for the model, wherein at least one of said requirements is defined using at least one value property.

CROSS-REFERENCE TO RELATED APPLICATION

This Application is a continuation-in-part of and claims priority toU.S. patent application Ser. No. 13/285016 filed on Oct. 30, 2011 thecontent of which is incorporated herein by reference in its entirety.

COPYRIGHT & TRADEMARK NOTICES

A portion of the disclosure of this document may contain materialsubject to copyright protection. Certain marks referenced herein may becommon law or registered trademarks of the applicant, the assignee orthird parties affiliated or unaffiliated with the applicant or theassignee. Use of these marks is for providing an enabling disclosure byway of example and shall not be construed to exclusively limit the scopeof the disclosed subject matter to material associated with such marks.

TECHNICAL FIELD

The disclosed subject matter generally relates to testing systembehavior in a computing environment.

BACKGROUND

Model based techniques may be used for modeling software systems bygenerating tests for verifying the behavior of a computing system onwhich the software is executed. A model includes a set of attributes inaddition to values for the attributes and corresponding restrictions onsaid values or value combinations. The set of valid value combinationsdefines the space to be tested.

In a Cartesian-product based model, the test space is defined as allpossible combinations of variable (i.e., attribute) values that are notruled out by restrictions. The size of a Cartesian-product based modelis the product of the number of values for each attribute (i.e., A₁*A₂*. . . *A_(n)), where A_(n) represents the number of valid values for then^(th) attribute. One would appreciate that the size of the model canbecome prohibitively large, depending on the number of attributes andthe possible number of values assigned to each attribute.

Depending on the testing environment, tests may be selected from largedata sets or large test suits where the set of values for one or moreattributes may be too large to be accommodated by the availableresources in a computing system under test. In some scenarios, there maybe multiple values that are equivalent with respect to a given testing.Thus, it may be desirable to select tests based on properties associateswith values, instead of the values themselves.

For example, in healthcare there are thousands of diagnosis codes.Testing all of them, not to mention combinations of all of them, withprocedure codes, for example, may consume a vast volume of resources. Itwould be desirable to reduce the number of tests by requiring coverageof groups of codes (e.g., blood vs. bone related diagnosis). Such groupsmay be semantic or procedural. That is, a group of values may share thesame processing path and hence only one value from each group may needto be covered.

Currently, implementing a grouping such as that noted above requireswriting a program or a script that transforms the original input valuesto the smaller set of groups or group representatives. The codingprocess is an expensive, time consuming step and requires skills thatare frequently not available to the novice members of test teams. A lessexpensive and more flexible alternative is desirable that can be used tosimplify the modeling of software system.

SUMMARY

For purposes of summarizing, certain aspects, advantages, and novelfeatures have been described herein. It is to be understood that not allsuch advantages may be achieved in accordance with any one particularembodiment. Thus, the disclosed subject matter may be embodied orcarried out in a manner that achieves or optimizes one advantage orgroup of advantages without achieving all advantages as may be taught orsuggested herein.

In accordance with one embodiment, a method for modeling a test space isprovided. The method comprises defining a coverage model including oneor more attributes, wherein respective values for the attributes areassigned, one or more definitions of value properties for saidattributes with assigned values, and one or more requirements that limitcombination of attribute values that are legal for the model, wherein atleast one of said requirements is defined using at least one valueproperty.

In accordance with one or more embodiments, a system comprising one ormore logic units is provided. The one or more logic units are configuredto perform the functions and operations associated with theabove-disclosed methods. In yet another embodiment, a computer programproduct comprising a computer readable storage medium having a computerreadable program is provided. The computer readable program whenexecuted on a computer causes the computer to perform the functions andoperations associated with the above-disclosed methods.

One or more of the above-disclosed embodiments in addition to certainalternatives are provided in further detail below with reference to theattached figures. The disclosed subject matter is not, however, limitedto any particular embodiment disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed embodiments may be better understood by referring to thefigures in the attached drawings, as provided below.

FIG. 1A illustrates an exemplary set of restrictions defined forattribute combinations in a model constructed to test a system.

FIGS. 1B through 1E are exemplary illustrations of a model whereinattributes are associated with one or more properties, in accordancewith one embodiment.

FIG. 2 is a flow diagram of an exemplary method for modeling a testspace for a system, by assigning properties to one or more attributes,in accordance with one embodiment.

FIGS. 3A and 3B are block diagrams of hardware and software environmentsin which the disclosed systems and methods may operate, in accordancewith one or more embodiments.

Features, elements, and aspects that are referenced by the same numeralsin different figures represent the same, equivalent, or similarfeatures, elements, or aspects, in accordance with one or moreembodiments.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

In the following, numerous specific details are set forth to provide athorough description of various embodiments. Certain embodiments may bepracticed without these specific details or with some variations indetail. In some instances, certain features are described in less detailso as not to obscure other aspects. The level of detail associated witheach of the elements or features should not be construed to qualify thenovelty or importance of one feature over the others.

In accordance with one or more embodiments, a coverage model is used totest a target system. The model defines variables (i.e., attributes),possible values for the attributes, and conditions or requirements toindicate when values for one or more attributes or value combinationsfor a plurality of attributes are valid or invalid. The set of validvalue combinations and requirements for combinations of attributes thatare to be included in the test plan define the coverage model.

The size of the test space for the model may be defined by the product(e.g., the Cartesian product) of attribute values taking into accountthe dictated conditions, requirements or restrictions. In a Cartesianproduct based model, the size of the test space is approximatelyproportional to the product of the number of values that can be assignedto each attribute. In one embodiment, to reduce the number of tests fortesting the system, a subset of the attributes whose combinations thatare to be covered may be defined by way of applying an algorithm (e.g.,a combinatorial algorithm) to filter out certain attribute combinations.

As such, in one embodiment, a combinatorial algorithm is used togenerate a relatively small set of tests that satisfy certaininteraction requirements between selected attributes. The requirementsfor the combination of attribute values may be provided as input to acombinatorial test design (CTD) engine. Given a Cartesian-product modelwith n attributes, the combinatorial algorithm finds a subset of validattribute value combinations in the test space that covers possiblecombinations of every m attributes, wherein m defines a certaininteraction level.

The interaction level, depending on implementation, refers to thecoverage of the selected subset of the test space, wherein the testspace covers the possible combinations of m number of attributes in theset defined by the respective coverage model—m is less than or equal tothe total number of attributes n in the model. As an example,interaction level two means that for every two attributes all or somevalid value combinations appear in the selected subset of the testspace. Empirical evidence shows that most bugs may be found when testingthe interesting interactions among a relatively small number ofattributes.

In accordance with one embodiment, Cartesian product based modeling maybe implement to allow a user (e.g., a user not skilled in developingtest models by way of scripting) to define relatively sophisticatedcoverage requirements without having to write scripts that transforminput data. A semantic abstraction of the model may be thus inherentlyinduced by providing an interface that allows the user to associateproperties with attribute values, and enhancing coverage requirementsyntax to allow conditions based on these properties.

In one implementation, the user may interact with the provided userinterface to (1) generate test suits by defining requirements based onproperties (as opposed to restrictions on properties) and (2) select atest by defining properties and requirements for the propertiesassociated with attribute values. For example, a system may be modeledbased on the following three attributes: (1) hardware platform, (2)operating system (OS), and (3) host bus adaptor (HBA). This hypotheticalsystem may include six different platforms, 17 different operatingsystems and 11 HBAs with incompatible components.

Referring to FIG. 1A, for example, in practice not all OSs may run onall platforms due to a type mismatch (e.g., Windows OS cannot run onpSeries computers), and not all HBAs may be used with every OS.Accordingly, to properly construct the model for this exemplary system,one may have to resort to using programming language expressions oralternatively define a requirement to avoid an illegal combination(e.g., “not allowed xServer and AIX.7”, “not allowed xServer and AIX.6”,“not allowed xBlade and AIX.7”, etc.).

Due to the number of restrictions involved, defining every singlerestriction based on the above approach may be a time consuming anderror prone process. As such, in one embodiment, the model isimplemented so that the system attributes may be grouped according totheir common properties or type. Referring to FIG. 1B, for example, amodel 110 is illustrated in which the possible attribute values areshown as a list associated with each attribute. As shown, the attribute“platform” may be assigned values xServer, xBlade, pServer, pBlade,etc.; and the attribute “OS” may be assigned values RHEL5.x, Win2k3,AIX5.x, AIX6.x, etc., for example.

Depending on implementation, the matching between attribute values maybe based on the attribute values association with a certain property.For example, certain OSs may run on both types of platforms, but othersmay only run on one type of platform. Accordingly, referring to FIG. 1C,each platform may be associated with a type “x” or “p”, and each OS maybe associated with one or both types “x” or “p”. In other words, theproperties for the attributes are defined per attribute, and therespective values for the properties are of a certain type.

As such, referring to FIGS. 1B and 1C, attributes values may be definedas a list associated with the attribute, with property columns, wherethe properties are given per attribute and their value may be of anytype. This is equivalent to defining a function over the values of anattribute. Partial functions (that are defined on part of the valuedomain) may be also of use. In one embodiment, for values for which thefunction is not defined, the default is to leave the current value.

Referring to FIG. 1D, attribute properties may also be used in visual orgraphical user interfaces to present or mark in abstract the limitationsor restrictions associated with one or more attributes included in themodel based on the semantic information given in the property values fora attribute. For example, depending on implementation, a certain color,font, or other property associated with a character that is used torepresent a attribute may indicate that one or more combinations arerequired or illegal. In FIG. 1D, for example, the illegal combinationsare shown with italic and bold properties with the attributesabstracted.

As such, adding properties to values may be done using an interactivegraphical user interface (GUI), as part of modeling a test domain by wayof a mechanism that imports tables in various formats or based on ananalysis of the frequency of occurrence of values. For example, in anexample scenario, the most frequently used 10 values or 10representatives of the next 90 most frequency used values may beconsidered. Of special interest are properties that describe methods tomitigate the transformation from ICD-9 to ICD-10 diagnosis codes inhealthcare systems.

Referring to FIG. 2, static analysis of the code under test may beoptionally used to produce groupings based on values that are equivalentwith respect to the code under test (S210). In one implementation,multiple properties may be assigned to a one or more attribute values(S220). Optionally, the different methods of assigning properties todifferent attribute values may be combined. Test coverage requirements,on attribute value combinations, may be defined by allowing the use ofproperty names instead of attribute names (S230).

Once the test coverage requirements are defined, a subset of a giventest suit may be selected, wherein the subset satisfies the requirementsdefined by the test coverage (S240). Accordingly, properties may be usein place of attributes to define a coverage requirement. For example,existing tests (or part of them) may be represented in terms ofdifferent properties, if the original values are missing but theproperties may still be deduced. The respective information may be usedduring test selection (or coverage analysis) when there are coveragerequirements that relate to properties.

Referring to FIG. 1E, in an example model, diagnosis codes (e.g., a setof 11 diagnosis codes) and procedure codes (e.g., a set of 11 procedurecodes) are used to define attribute values. In this example, frequency(e.g., set of {Low, Medium, High}) and importance (e.g., set of {Low,Medium, High}) are the respective properties defined for the diagnosiscode and the procedure code. In the above example, the followingcombinations may be considered for the purpose of testing the modelunder test:

-   -   1. All combinations of Diagnosis Code and Procedure Code        (11*11=121 combinations)    -   2. All combinations of Diagnosis Code Frequency and Procedure        Code Importance (3*3=9 combinations)    -   3. All combinations of Diagnosis Code Frequency and Procedure        Code (3*11=33 combinations)

Requirements defined in #1 reflect known CTD practices involving thedesignation of combinations of attributes to be tested together.Requirements defined in #2 and #3 are different in that instead ofdesignating combinations of attributes, combinations of attributeproperties are designated for the purpose of testing. This approach maybe applied not only to CTD test generation but also to test selection,depending on implementation.

It is noteworthy that in the above example, some of the combinationsincluded above can be ruled out by restrictions. For example consider:

-   -   1. Don't allow Diagnosis Code=31415 && Procedure Code=A14    -   2. Don't allow Diagnosis Code Frequency=Low && Procedure Code        Importance=Low    -   3. Don't allow Diagnosis Code=31415 && Procedure Code        Importance=Medium

The above disclosed method enhances Cartesian product based modeling ina way that allows a user to more easily define fairly sophisticatedrestrictions without having to use complex programming language syntax.Furthermore, a semantic abstraction of the model is induced by providingan interface that allows the user to associate properties with attributevalues, and enhancing requirement syntax to allow conditions based onsaid properties. Based on the above, one or more embodiments may beutilized to make the modeling of a system simpler without reducing theefficacy of the model, resulting in reduced costs and increased quality.

In different embodiments, the claimed subject matter may be implementedas a combination of both hardware and software elements, oralternatively either entirely in the form of hardware or entirely in theform of software. Further, computing systems and program softwaredisclosed herein may comprise a controlled computing environment thatmay be presented in terms of hardware components or logic code executedto perform methods and processes that achieve the results contemplatedherein. Said methods and processes, when performed by a general purposecomputing system or machine, convert the general purpose machine to aspecific purpose machine.

Referring to FIGS. 3A and 3B, a computing system environment inaccordance with an exemplary embodiment may be composed of a hardwareenvironment 1110 and a software environment 1120. The hardwareenvironment 1110 may comprise logic units, circuits or other machineryand equipments that provide an execution environment for the componentsof software environment 1120. In turn, the software environment 1120 mayprovide the execution instructions, including the underlying operationalsettings and configurations, for the various components of hardwareenvironment 1110.

Referring to FIG. 3A, the application software and logic code disclosedherein may be implemented in the form of computer readable code executedover one or more computing systems represented by the exemplary hardwareenvironment 1110. As illustrated, hardware environment 110 may comprisea processor 1101 coupled to one or more storage elements by way of asystem bus 1100. The storage elements, for example, may comprise localmemory 1102, storage media 1106, cache memory 1104 or othercomputer-usable or computer readable media. Within the context of thisdisclosure, a computer usable or computer readable storage medium mayinclude any recordable article that may be utilized to contain, store,communicate, propagate or transport program code.

A computer readable storage medium may be an electronic, magnetic,optical, electromagnetic, infrared, or semiconductor medium, system,apparatus or device. The computer readable storage medium may also beimplemented in a propagation medium, without limitation, to the extentthat such implementation is deemed statutory subject matter. Examples ofa computer readable storage medium may include a semiconductor orsolid-state memory, magnetic tape, a removable computer diskette, arandom access memory (RAM), a read-only memory (ROM), a rigid magneticdisk, an optical disk, or a carrier wave, where appropriate. Currentexamples of optical disks include compact disk, read only memory(CD-ROM), compact disk read/write (CD-R/W), digital video disk (DVD),high definition video disk (HD-DVD) or Blue-ray™ disk.

In one embodiment, processor 1101 loads executable code from storagemedia 1106 to local memory 1102. Cache memory 1104 optimizes processingtime by providing temporary storage that helps reduce the number oftimes code is loaded for execution. One or more user interface devices1105 (e.g., keyboard, pointing device, etc.) and a display screen 1107may be coupled to the other elements in the hardware environment 1110either directly or through an intervening I/O controller 1103, forexample. A communication interface unit 1108, such as a network adapter,may be provided to enable the hardware environment 1110 to communicatewith local or remotely located computing systems, printers and storagedevices via intervening private or public networks (e.g., the Internet).Wired or wireless modems and Ethernet cards are a few of the exemplarytypes of network adapters.

It is noteworthy that hardware environment 1110, in certainimplementations, may not include some or all the above components, ormay comprise additional components to provide supplemental functionalityor utility. Depending on the contemplated use and configuration,hardware environment 1110 may be a desktop or a laptop computer, orother computing device optionally embodied in an embedded system such asa set-top box, a personal digital assistant (PDA), a personal mediaplayer, a mobile communication unit (e.g., a wireless phone), or othersimilar hardware platforms that have information processing or datastorage capabilities.

In some embodiments, communication interface 1108 acts as a datacommunication port to provide means of communication with one or morecomputing systems by sending and receiving digital, electrical,electromagnetic or optical signals that carry analog or digital datastreams representing various types of information, including programcode. The communication may be established by way of a local or a remotenetwork, or alternatively by way of transmission over the air or othermedium, including without limitation propagation over a carrier wave.

As provided here, the disclosed software elements that are executed onthe illustrated hardware elements are defined according to logical orfunctional relationships that are exemplary in nature. It should benoted, however, that the respective methods that are implemented by wayof said exemplary software elements may be also encoded in said hardwareelements by way of configured and programmed processors, applicationspecific integrated circuits (ASICs), field programmable gate arrays(FPGAs) and digital signal processors (DSPs), for example.

Referring to FIG. 3B, software environment 1120 may be generally dividedinto two classes comprising system software 1121 and applicationsoftware 1122 as executed on one or more hardware environments 1110. Inone embodiment, the methods and processes disclosed here may beimplemented as system software 1121, application software 1122, or acombination thereof. System software 1121 may comprise control programs,such as an operating system (OS) or an information management system,that instruct one or more processors 1101 (e.g., microcontrollers) inthe hardware environment 1110 on how to function and processinformation. Application software 1122 may comprise but is not limitedto program code, data structures, firmware, resident software, microcodeor any other form of information or routine that may be read, analyzedor executed by a processor 1101.

In other words, application software 1122 may be implemented as programcode embedded in a computer program product in form of a computer-usableor computer readable storage medium that provides program code for useby, or in connection with, a computer or any instruction executionsystem. Moreover, application software 1122 may comprise one or morecomputer programs that are executed on top of system software 1121 afterbeing loaded from storage media 1106 into local memory 1102. In aclient-server architecture, application software 1122 may compriseclient software and server software. For example, in one embodiment,client software may be executed on a client computing system that isdistinct and separable from a server computing system on which serversoftware is executed.

Software environment 1120 may also comprise browser software 1126 foraccessing data available over local or remote computing networks.Further, software environment 1120 may comprise a user interface 1124(e.g., a graphical user interface (GUI)) for receiving user commands anddata. It is worthy to repeat that the hardware and softwarearchitectures and environments described above are for purposes ofexample. As such, one or more embodiments may be implemented over anytype of system architecture, functional or logical platform orprocessing environment.

It should also be understood that the logic code, programs, modules,processes, methods and the order in which the respective processes ofeach method are performed are purely exemplary. Depending onimplementation, the processes or any underlying sub-processes andmethods may be performed in any order or concurrently, unless indicatedotherwise in the present disclosure. Further, unless stated otherwisewith specificity, the definition of logic code within the context ofthis disclosure is not related or limited to any particular programminglanguage, and may comprise one or more modules that may be executed onone or more processors in distributed, non-distributed, single ormultiprocessing environments.

As will be appreciated by one skilled in the art, a software embodimentmay include firmware, resident software, micro-code, etc. Certaincomponents including software or hardware or combining software andhardware aspects may generally be referred to herein as a “circuit,”“module” or “system.” Furthermore, the subject matter disclosed may beimplemented as a computer program product embodied in one or morecomputer readable storage medium(s) having computer readable programcode embodied thereon. Any combination of one or more computer readablestorage medium(s) may be utilized. The computer readable storage mediummay be a computer readable signal medium or a computer readable storagemedium. A computer readable storage medium may be, for example, but notlimited to, an electronic, magnetic, optical, electromagnetic, infrared,or semiconductor system, apparatus, or device, or any suitablecombination of the foregoing.

In the context of this document, a computer readable storage medium maybe any tangible medium that can contain, or store a program for use byor in connection with an instruction execution system, apparatus, ordevice. A computer readable signal medium may include a propagated datasignal with computer readable program code embodied therein, forexample, in baseband or as part of a carrier wave. Such a propagatedsignal may take any of a variety of forms, including, but not limitedto, electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device.

Program code embodied on a computer readable storage medium may betransmitted using any appropriate medium, including but not limited towireless, wireline, optical fiber cable, RF, etc., or any suitablecombination of the foregoing. Computer program code for carrying out thedisclosed operations may be written in any combination of one or moreprogramming languages, including an object oriented programming languagesuch as Java, Smalltalk, C++ or the like and conventional proceduralprogramming languages, such as the “C” programming language or similarprogramming languages.

The program code may execute entirely on the user's computer, partly onthe user's computer, as a stand-alone software package, partly on theuser's computer and partly on a remote computer or entirely on theremote computer or server. In the latter scenario, the remote computermay be connected to the user's computer through any type of network,including a local area network (LAN) or a wide area network (WAN), orthe connection may be made to an external computer (for example, throughthe Internet using an Internet Service Provider).

Certain embodiments are disclosed with reference to flowchartillustrations and/or block diagrams of methods, apparatus (systems) andcomputer program products according to embodiments. It will beunderstood that each block of the flowchart illustrations and/or blockdiagrams, and combinations of blocks in the flowchart illustrationsand/or block diagrams, can be implemented by computer programinstructions. These computer program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

These computer program instructions may also be stored in a computerreadable storage medium that can direct a computer, other programmabledata processing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablestorage medium produce an article of manufacture including instructionswhich implement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

The flowchart and block diagrams in the figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods and computer program products according to variousembodiments. In this regard, each block in the flowchart or blockdiagrams may represent a module, segment, or portion of code, whichcomprises one or more executable instructions for implementing thespecified logical function(s). It should also be noted that, in somealternative implementations, the functions noted in the block may occurout of the order noted in the figures.

For example, two blocks shown in succession may, in fact, be executedsubstantially concurrently, or the blocks may sometimes be executed inthe reverse order, depending upon the functionality involved. It willalso be noted that each block of the block diagrams and/or flowchartillustration, and combinations of blocks in the block diagrams and/orflowchart illustration, can be implemented by special purposehardware-based systems that perform the specified functions or acts, orcombinations of special purpose hardware and computer instructions.

The claimed subject matter has been provided here with reference to oneor more features or embodiments. Those skilled in the art will recognizeand appreciate that, despite of the detailed nature of the exemplaryembodiments provided here, changes and modifications may be applied tosaid embodiments without limiting or departing from the generallyintended scope. These and various other adaptations and combinations ofthe embodiments provided here are within the scope of the disclosedsubject matter as defined by the claims and their full set ofequivalents.

What is claimed is:
 1. A method executable on one or more processors formodeling a test space, the method comprising: defining a coverage modelincluding: one or more attributes, wherein respective values for theattributes are assigned, one or more definitions of value properties forsaid attributes with assigned values, and one or more requirements thatdefine combination of attribute values to be covered by the model,wherein at least one of said requirements is defined using at least onevalue property, instead of an attribute value.
 2. The method of claim 1wherein one or more requirements are defined based on a common propertyshared among at least two attributes.
 3. The method of claim 1 whereindefining requirements applicable to attribute value combinations basedon the value property is accomplished by way of interacting with agraphical user interface.
 4. The method of claim 3 wherein a colorcoding scheme is used to identify value property combinations that donot meet defined requirements in the model by marking a propertyassociated with an attribute in a certain color.
 5. The method of claim3 wherein a scheme is used to identify value property combinations thatdo not meet defined requirements in the model by configuring a propertyassociated with an attribute in a certain font.
 6. The method of claim 3wherein a scheme is used to identify value property combinations that donot meet defined requirements in the model by configuring a propertyassociated with an attribute in a visually distinctive manner
 7. Themethod of claim 3 wherein the attribute value properties for selectedattributes are displayed in a table and the requirements are defined bymarking rows or columns in the table.
 8. The method of claim 2 whereinvalue property combinations for selected properties are displayed in atable, and the requirements are defined by marking rows or columns inthe table.
 9. The method of claim 1 wherein a value property for aattribute defines a type associated with the attribute.
 10. The methodof claim 1 further comprising testing the model using a set of validattribute value combinations.
 11. A system comprising one or moreprocessors for executing a method for modeling a test space, the systemfurther comprising: a logic unit for defining a coverage modelincluding: one or more attributes, wherein respective values for theattributes are assigned, one or more definitions of value properties forsaid attributes with assigned values, and one or more requirements thatdefine combination of attribute values to be covered by the model,wherein at least one of said requirements is defined using at least onevalue property, instead of an attribute value.
 12. The system of claim11 wherein one or more requirements are defined based on a commonproperty shared among at least two attributes.
 13. The method of claim11 wherein defining requirements applicable to attribute valuecombinations based on the value property is accomplished by way ofinteracting with a graphical user interface.
 14. The method of claim 13wherein a color coding scheme is used to identify attribute valuecombinations that are defined for the model by marking a propertyassociated with a attribute in a certain color.
 15. The method of claim13 wherein a scheme is used to identify attribute value combinationsthat are defined for the model by configuring a property associated witha attribute in a certain font.
 16. A computer program product comprisingprogram code embedded in a non-transitory data storage medium, whereinexecution of the program code on a computer causes the computer to:define a coverage model including: one or more attributes, whereinrespective values for the attributes are assigned, one or moredefinitions of value properties for said attributes with assignedvalues, and one or more requirements that define combination ofattribute values to be covered by the model, wherein at least one ofsaid requirements is defined using at least one value property, insteadof an attribute value.
 17. The computer program product of claim 16wherein one or more requirements are defined based on a common propertyshared among at least two attributes.
 18. The computer program productof claim 16 wherein defining requirements applicable to attribute valuecombinations based on the value property is accomplished by way ofinteracting with a graphical user interface.
 19. The computer programproduct of claim 18 wherein a color coding scheme is used to identifyattribute value combinations that are defined for the model by marking aproperty associated with an attribute in a certain color.
 20. Thecomputer program product of claim 18 wherein a scheme is used toidentify attribute value combinations that are defined for the model byconfiguring a property associated with an attribute in a certain format.